A short story by Aesop (author of Aesop's Fables)

The Wolf And The House-dog

A Wolf, meeting with a big, well-fed Mastiff, having a wooden collar about his neck, inquired of him who it was that fed him so well, and yet compelled him to drag that heavy log about wherever he went. "The master," he replied. Then, said the Wolf: "May no friend of mine ever be in such a plight; for the weight of this chain is enough to spoil the appetite."